Vertical current mineral concentrator



March 16, 1948. J ANDERSON 2,437671 VERTICAL CURRENT MINERAL CONCENTRATOR Filed Feb. 11, 1944 I NYE/W012 uomv (Aerie fi/vazesolv Patented Mar. 16, 1948 VERTICAL CURRENT MINERAL- CONCENTRATOR John Carter Anderson, Los Angeles, Calif.

Application February 11, 1944, Serial No. 521,921

3 Claims.

This invention relates to the concentration of ores, gravel, and the like to recover desired mineral values from gangue, waste, and undesired minerals, and employs a so-called sink and float type of apparatus.

An important object of my invention is to provide a simple apparatus and simple procedures for separating desired heavy minerals, and another object is to obtain such concentration through the employment of only water and the ore or gravel itself as concentrating media.

I have discovered that crushed or screened ore or gravel, flowed into a concentrating chamber with the usual feed water, may be employed, in conjunction with a relatively small quantity of water injected into the lower portion ofthe concentrating chamber, to form from its own constituents a heavy separating medium in the lower portion of the chamber. This heavy medium is mildly agitated by the injected water which is distributed uniformly through it without creating rising currents of material velocity, so that the desired heavy mineral settles, by displacement of the lighter material, into the IOWer portion of the chamber without interference from rising water currents. The desired mineral may be the heavy medium itself, but

if present in small quantity it settles through the heavy medium into the bottom of the chamher. In all cases the lighter undesired minerals and gangue remain above said heavy medium and are discharged as tailings from the top-of the receptacle into a launder Or other disposal device. Thus the heavy separatin medium so produced is a self-maintaining and self-cleaning medium which consists of the heaviest ingredient of the ore or gravel of which there is any appre-- The gentle agitation caused by the injected water maintains a Quicksand ciable proportion.

type of condition within the receptacle which permits particles of higher specific gravity to displace particles of lower specific gravity. Thus, higher specific gravity particles settle as lower specific gravity particles are displaced upward.- toward the overflow, Where substantial proportions of heavy desired mineral exist in the feed, such as scheelite, galena, or magnetite, the concentrate settling in the vessel is regularly removed in any desired manner, either intermittently or continuously, so as to'keep the top level of the concentrate in the chamber either within fixed limits or at a constant level. Where very little of the desired heavy mineral is present; such as free gold, it is allowed to settle. through 2 the heavy medium and to; accumulate for removal atirregular intervals. Where reference is made to light and heavy materials, the terms are intended to signify materials of low and high'specific gravities, respectively.

While water currents of relatively high rising velocity have been used for mineral separation, such hydraulic classif cation relies upon the dif ferences between the falling velocities of the various mineral particles in the feed, whether of low or high specific gravity, and is, unable to separate large particles of low specific gravity from smaller particles of high specific gravity having a similar falling velocity Will be apparent that the present" method differs therefrom inasmuch as the former method removes the particles havinglower falling, velocity from those having higher falling velocity, whether desired mineral or waste, by the rising velocity of the injected water, the particles of lower falling velocitybeing carried out of the receptacle by the Velocity of the rising current, thus carrying away objectionable amounts of fine particles of the desired mineral whose falling velocities are unable to overcome the Velocity of the rising current, while leaving in the concentrate the larger grainsof undesired mineral whose falling velocities are greater thanthe velocity of the rising current.

My operation of my apparatus also differs from that wherein a special heavy medium is artificially prepared from finely divided Weighting material, or otherwise, to yield a constant specific gravity medium heavier than the materials to be rejected but light enough for the desired heavy concentrate materials to sink therethrough.

Since some of such specially preparedheavy medium is. flowed upward and discharged with the tailings, it must be recovered therefrom, reconditioned, and continuously returned; also some of the heavy medium necessarily escapes with the concentrates and' must be recovered, reconditioned and returned. The operation of the present device also difiers from prior methods which are useful principally on screened feeds having upper and lower size limits, e. g.,. between 1%" and My, wherein the viscosity of an artificial heavy-medium employed overcomes the weight differential of smaller particles of the heavy mineral and rejects them as waste; inasmuch as my present apparatus may be used for separating unscreened material, or. material screened only as to its upper limit, because the fines are notnot" through. the heavy medium and constituting 3 part of the concentrate which is being regularly removed from the bottom of the apparatus, and the light fines flowing off the top thereof.

The operation of the present apparatus, as distinguished from prior methods, relies upon the differences in specific gravity between the various components of the feed material itself and not upon any lifting effect of water or other fluid currents, and not upon the lifting efiect or supporting effect of a screen as in jigs. Rather, a quicksand type of condition exists and the action is one of displacement of lower specific gravity materials by higher specific gravity materials regardless of particle size. This also distinguishes from separation by jigs. While the feed material will commonly be referred to hereinafter as ore, the term is intended to include placer gravel, and tailings from old dumps and other low grade material, as well as regular mine production, and also any other feed material composed of particles of different specific gravity which it may be desired to separate, as, for example, in the removal of soil particles from seeds or grain.

The invention also includes apparatus for effecting the quicksand type of sink and float separation herein described. This comprises a header adapted to be disposed in a concentrating chamber and provided with water discharge ports for distributing water uniformly through a body of ore material accumulated between the header and the walls of the chamber. In a preferred form the header is a container closed except for an inlet and the water discharge ports, and

adapted to be submerged in an ore and water body in the chamber. Preferably the walls of the header and chamber are inclined and converse downwardly with the header walls parallel to the chamber walls, the header being vertically adjustable to vary the agitation effects of the water streams as the feed varies in the size, shape and weight of its component particles. The invention includes a side ore feed to the chamber as well as a top ore feed upon the header.

In the accompanying drawing wherein certain embodiments of the invention are disclosed by way of illustration:

Fig. 1 is principally a vertical section, portions being shown in elevation, indicating one form which the invention may take;

Fig. 2 is a plan view of the structure shown in Fig. 1, being taken from line 2-2 of Fig. 1;

Fig. 3 is principally a vertical section showing a modification of apparatus which may be used, portions being shown in elevation;

Fig. 4 is a plan view of the form shown in Fig. 3, being taken from line 44 of Fig. 3; and

Fig. 5 is chiefly a vertical section of another modification, parts being shown in elevation,

Referrin to the form of the invention disclosed in Figs. 1 and 2, a concentrating receptacle ls'shown in the form of a tank In which is substantially rectangular in transverse section and has its four walls converging downwardly to form an inverted truncated pyramid. Within the tank In a water distributing header [2 is centrally disposed to provide a peripheral concentrating chamber l4 between the walls of the tank I and the walls of the header l2. Crushed ore and water are supplied to one side of the receptacle [0 in the direction of arrows l by means of a wide feed apron or feed launder i6 having sideboards I! which extend from the feed apron l6 along the sides of the receptacle H) to an equally wide discharge apron or launder l8 positioned at approximately the same level as apron l6 and arranged for disposal of the tailings in any suitable manner not shown.

The lower end of the receptacle i0 is provided with a T 22 carrying any desired means for removal of the concentrate. As shown, a plug 24 is provided in one branch of the T and a swing valve 25 is pivoted at 26 on the other branch 28 in order normally to close an arcuate opening 29 at the end of the branch 28, any suitable stop such as indicated at 30 bein provided to limit the movement of the valve 25 to closed position. In the event that two heavy minerals stratify sufficiently so that they may be separately recovered as separate concentrates, a second outlet 32 is positioned at a higher level on the receptacle l0 and provided with appropriate means such as a gate valve 33 from which concentrate may be withdrawn as desired from the upper level of the accumulated bed.

The water distributing header l2, which is the important feature of the present invention, is comprised of two parts of pyramidal shape, these being a lower section 35 having the shape of an inverted truncated pyramid, and an upper section 36 in the shape of a truncated pyramid which is rigidly secured to the top of lower section 35. The truncated bottom of the lower section 35 has an opening fitted with an interchangeable nipple or short pipe connection 31 adapted for the injection of water into the lower part of the receptacle ID for proper agitation therein. By changing the nipple 37 to one of different here to provide whatever capacity is required, any degree of agitation and amount of water desired in the lower part of the receptacle It] can be readily attained. In order to obtain desired agitation throughout the peripheral concentrating chamber M the sections 35 and 3B of the header 12 are provided with small spaced openings or ports 38 which are of such size and distribution as compared with the width of the chamber I4 between the walls of the header l2 and the receptacle [0 as to give the desired degree of agitation in the ore body accumulating in said concentrating chamber l4, as will be more fully explained hereinafter. The Walls of the lower section 35 of the header [2 are preferably disposed in parallelism with the walls of the receptacle ll) inasmuch as uniformly good agitation is obtained in that manner. In the event that it is desirable to direct quantities of wash water down over the walls of the upper section 36, downwardly directed slots 39 may be provided in a neck 40 formed as an extension of the section 36 of the header l2,

For the purpose of adjustably supporting the header l2 in operative position and also for supplying water into said header I2, the lower end of a water feed pipe 42 is threaded into the neck 40, the pipe 42 extending upwardly through an opening in a supporting beam 43 which may be carried by the sideboards H, a nut M adapted for adjusting the height of the header l2 being threadedly mounted on the pipe 42 for rotation into any adjusted position where it is secured as by means of a lock nut 45. The water supply to header l2 may be regulated by a valve 46 in the pipe 42.

In the modification shown in Figs. 3 and 4, the ore feed is supplied to the concentrating receptacle 59 through a vertically arranged, centrally disposed up-flow feed pipe 5| which passes centrally up through a Water header 52 and adjustably supports the same as by being threadedly mounted in a collar 53 secured to or integral with the top of the header 52. The concentrating receptacle 5c is in the form of an inverted truncated cone in which the header 52 defines a peripheral concentrating chamber 54. The feed pipe Si is supported by being fixedly mounted in a fitting or packing gland 55 suitably secured in the truncated lower end of the receptacle 50. The width of the chamber 5 1 is adjusted by running the header 52 up or down on its threaded mounting on the feed pipe iii. In this form of the invention a T 58 is disposed close to the fitting 55 for removal of concentrate, this T 58 being provided in practice with any suitable type of valve means, not shown, which, however, may be such as indicated in Fig. 1.

Similarly to the form of Figs. 1 and 2, the water header 52 of Figs. 3 and 4 comprises a lower section 59 and an upper section 60, the lower section 59 being in the form of an inverted truncated cone, and the upper section 56 being in the form of a truncated cone rigidly secured to the upper portion of the section 59, both of these sections being provided with water distribution ports 62 suitably disposed to produce the desired agitation, as in the case of the form previously described. Special openings 63 are placed in the bottom wall to provide proper water supply and agitation, and to eiiect a function conforming in general with that of nipple 37 of the form of Fig. 1. Thus, agitation in the bottom of chamber 54 may be effected, and also suificient water supplied to compensate for loss when withdrawing concentrate. Water is fed into the water header 52 by means of a pipe 5d, which may be controlled by a valve or, the lower end of the pipe 64 being secured in the upper wall of the header section so. Water and tailings discharged by the form of the device of Figs. 3 and 4 overflow the edges of the receptacle 5i? and pass into a circular launder 6% provided with walls 58 which feed the tailings into a suitable trough 69 for further disposition.

In the modification of Fig. 5, the concentrating receptacle is and the water header 72 may be circular in cross section and in general of inverted conical shape as in the form of Figs. 3 and 4, and the ore is fed from an overhead discharge opening it centrally onto the top of the water header l2, whence the heavy materials pass into the peripheral concentrating chamber 14. The water header i2 is supported on a water supply pipe #5 secured to a neck It on the top of the water header 12, the water pipe I5 being in turn supported in any suitable manner not shown.

The ore feed passing down onto the top of the water header 72 through the openings 13 is conducted by a suitable feed launder l8 leading from an ore supply. As in the header construction of Fig. 3, the header 72 comprises a lower section 80 and an upper section 82, the lower section being in the form of an inverted truncated cone and the upper section in the form of a truncated cone secured rigidly to the upper edge of the lower section as, both sections being provided with water distributing ports 83, and the lower section being provided with a downwardly directed port 84 adapted to create proper agitation in the bottom of the concentrating receptacle '10 as in the case of the nipple 37 of Fig. 1. Water fed into the header "l2 may be regulated by a valve 85 on pipe Tailings and water overflow the top of the concentrating receptacle i0 and pass into a launder to having side walls $1 which direct the tailings and water into a trough 88 or the like for suitable disposition. Concentrates are recovered from the bottom of the concentrating receptacle 1!] as through a T 93 which may be provided with a plug 92 at one outlet and with a swing valve 93.pivoted at 94 on the other outlet, as in the case of the construction of Fig. 1.

When operating the process of my present invention, the principle of mineral concentration is the same regardless of which form of apparatus disclosed is employed. This is true whether the ore feed is supplied to one side of the concentrating receptacle if] in the form of Figs. 1 and 2, or is supplied onto the top walls of the water headers 52 and 12 of the forms of Figs. 3 and 5. For this reason the concentrating phenomenon will be described by reference to the form of Figs. 1 and 2.

In initiating operation of the method, the crushed ore fed over the feed apron H5 in the direction of arrows I 5, soon fills the peripheral concentrating chamber i4 between the walls of the concentrating receptacle ID and those of the header !2, the accompanying feed water passing off over the discharge apron i8 and carrying ofi the tailings. Injected water supplied by the pipe 2 to the header i2 is distributed into the concentrating chamber i 4 through the water outlets or ports 38 and through the water outlet nipple 31 under sufficient pressure to agitate the mineral in the concentrating chamber I4 without imparting sufficient water velocity to create substantial lifting effects upon the heavy particles in the ore. The result is merely a mild agitation which permits the desired heavy mineral components of the ore to settle in the concentrating chamber hi due to their greater specific gravity, and thereby displace the gangue and lighter undesired minerals that may be present, thus causing the latter to be gradually .moved to the top of the ore body in the concentrating chamber M by reason of their lower specific gravity. For each ore feed, the water header I2 is adjusted in the concentrating chamber id and the supply of water leaving the ports 38 is correspondingly adjusted, so that that agitation is obtained in the lower part of the concentrating chamber I l for the particular ore in question, which permits the heavy minerals to sink, and causes the light materials that are initially present to rise by reason of displacement. Whatever the heavy mineral found in any ore feed, the required conditions can be relatively easily determined. In this manner a heavy mineral surface is established, below which the lighter minerals do not settle but remain at the top and pass on with the tailings. In this manner also, the desired heavy mineral component automatically builds up its own heavy medium which excludes the lighter materials, as just described. Since the agitation is gentle, and since the water currents are insufiicient to lift the desired heavy mineral, substantially all of the heavy mineral is recovered as concentrate and the separation is comparatively clean because the lighter minerals cannot sink into the heavy medium. As the heavy mineral medium builds up in the concentrating chamber is, the concentrate is withdrawn from the bottom of the receptacle It! as by way of the swing valve 25 on the T 22, or by any other appropriate means.

The action of the gentle agitation produced is readily accomplished with a limited amount of injected water. Ordinarily, the quantity of water at any given time is only approximately that sufiicient to fill the voids in the mineral bed without keeping the minerals in suspension. Since the phenomenon is dependent upon relative specific gravities and consequent displacement, it is relatively immaterial whether the mineral particles are small and have low falling velocities or are large and have high falling velocities. Therefore, all desired heavy minerals may be recovered regardless of particle size because of the fact that with such low water velocities as are employed, the heavy particles sink through the water and through the lighter gangue and light minerals not desired, and are collected with the larger particles of the same heavy material.

Specific examples where this process may be employed are found in the treatment of low grade iron ore where the iron mineral is recovered as a concentrate and at the same time constitutes the body of heavy medium accumulated in the concentrating chamber; the treatment of placer gravel containing gold and heavy black sand, the black sand forming the heavy medium and the gold sinking therethrough to form a concentrate recovered from the bottom of the concentrating chamber; and the treatment of sulphide ores such as galena ores where the sulphide constitutes both the heavy medium and the concentrate recovered. Where the ore contains two valuable minerals, for example an iron or other valuable mineral and free gold, the free gold will sink to the bottom of the concentrating chamber under the influence of the water agitation, and the iron mineral, for example, pyrite, will form both the heavy medium in the concentrating chamber and a desired concentrate. In the latter instance, the gold will be drawn off at suitable intervals from the bottom of the concentrating chamber as through the T 22 of Fig. 1, and the iron mineral will be drawn off as desired through a higher outlet connection such as the valve 33 of Fig. 1.

The process may also be applied to an ore containing only a small proportion of heavy valuable mineral, the rest of the ore being mineral or other material of lower specific gravity which it is desired to discharge as waste, an example of which is an ore carrying scheelite in a garnet gangue. Here the concentrating chamber may be filled with a foreign mineral having a specific gravity between those of scheelite and garnet, for example hematite or magnetite. The hematite or magnetite will then constitute the heavy medium filling the concentrating chamber, and the scheelite will sink through it while the garnet will float on its surface and be carried oil in the tailings. Since the water pressure producing the agitation is not suflicient to establish currents to carry off any of the artificial heavy medium supplied, and, since the scheelite is much heavier and settles into the bottom of the receptacle constituting the concentrating chamber whence it is drawn from time to time as a concentrate, the volume of the body of foreign heavy medium will remain substantially constant.

Where an ore contains several valuable minerals heavier than the gangue and undesired mate'- rials, several units of my apparatus may be employed, the heaviest mineral forming the heavy medium and concentrate in the first unit, the re maining material being removed as tailings and passed into the second unit wherein the next heaviest material is separated as the heavy medium and concentrate, and the tailings from the second unit being treated in a third unit for recovery of a third heavy mineral, if present in the ore.

While the present process is adapted to the treatment of the whole of a crushed ore, including both the larger sizes and the smaller sizes, it may be faster from an operating standpoint to screen the crushed ore and treat the larger sizes in one apparatus and the smaller sizes in another apparatus. Thus, when treating the lar er sizes a higher water pressure and greater volume of water may be passed into the bed of heavy medium for proper agitation, without elevating the particles of the heavy mineral, than can be accomplished if the fines are also to be recovered. This is because a water flow through the heavy medium that merely serve to agitate a bed of the coarser sizes may tend to lift and float out fines of the same heavy mineral because the falling velocity of the extremely fine material may be too low to overcome the upward water flow. On the other hand, it is also possible to operate by carrying over the fines with the heavier Water flow, then screening the tailings to remove the large particles of the gangue, and then treating the fine materials passing through the screen in a second unit for concentration of the finer portion of the desired heavy material.

As has been previously indicated, the amount of agitation in the heavy medium bed may be decreased or increased by adjusting the pressure of the water being distributed into said bed or body, and by raising or lowering the header to adjust the distance between the sides of the header I2 and the sides of the receptacle I0 constituting the concentrating chamber. It is to be noted that there is no partition or other obstruction across the top of the concentrating chamber between the water header l2 and the walls of receptacle l9 of Fig. 1, nor between the center ore feed and the overflow at the periphery of the receptacles 50 and 10 of Figs. 3 and 5. This permits free paths for movement of the gangue and other materials constituting the tailings across the concentrating chamber from the feed to the discharge point. This is important because I have found that if the feed material is diverted downward below the water level by a partition or baffle, a rising current is created from the under side of the partition or bafile of sufficient strength and turbulence to lift out and discharge portions of the valuable heavy minerals desired.

In distributing water from the water header into the ore bed in the concentrating chamber, a flow of determined pressure and volume may be continuous, or the water may be introduced to form a pulsating current to create the desired agitation. In either event the water flow will be only that required to produce the described effects. As has been pointed out, valuable heavy mineral of fine mesh can be recovered by this process when operating with very low water velocity because differences in specific gravity are the factors controlling the separation. In prior methods, there is a limitation upon the lower particle size that can be recovered as concentrate, which is due to the viscosity of the heavy medium and to the increase in viscosity which follows when the proportion of heavy weighting material in the heavy medium is increased to provide the separating density necessary to reject heavier waste materials; Such limitation due to viscosity of the heavy medium does not affect the operation of my method nor prevent the settling out of the desired heavy particles from the gangue or through lighter materials so long as the velocity of the agitating water is less than the falling velocity of the particles being separated as concentrate and sinking into the lower portion of the concentrating chamber.

While I have described certain preferred embodiments of the invention and have illustrated certain apparatus which may be employed, it is understood that many modifications will occur to those skilled in the art and therefore I intend to cover all such variations as fall within the scope of the appended claims.

I claim as my invention:

1. Apparatus for concentrating ores comprising: a concentrator receptacle; a water distributing header disposed within said receptacle and establishing a concentrating chamber around the header, said receptacle and header having sloping downwardly converging walls, the receptacle walls being respectively substantially parallel to corresponding header walls, said header having a plurality of water discharge ports for distributing Water through a mineral bed accumulated in said concentrating chamber; means to supply water to said header; means to supply ore to said receptacle; means adapted to adjust the header and vary the width of the concentrating chamber between said walls to regulate the effects of water distribution into ore in said chamber; means to receive tailings from the top to said receptacle; and means to withdraw concentrate from the lower portion of said receptacle.

2. Apparatus for concentrating ores comprising: a concentrator receptacle; a water distributing header disposed within said receptacle and establishing a concentrating chamber around the header, said header having top walls positioned below the top of the receptacle, and said header having a plurality of water discharge ports for distributing water through a mineral bed accumulated in said concentrating chamber; means to supply water to said header, means to supply ore to said receptacle; means to direct wash water for said water supply means onto said top header walls; means to receive tailings from the top of said receptacle; and means to withdraw concentrate from the lower portion of said receptacle.

3. Mineral concentrating apparatus comprising: a receptacle having sloping downwardly con. verging walls; a water distributing header disposed within said receptacle and having s oping downwardly converging walls substantially parallel to the walls of said receptacle and establishing a peripheral concentrating chamber between the receptacle walls and the header walls; means to supply ore feed to the upper portion of said receptacle; a tailings discharge from the top of said receptacle; means to supply water under pressure to said header, said header having spaced outlets for distribution of water into said concentrating chamber; means to adjust said header and vary the effects of water distribu tion; means adjacent the bottom of said receptacle for removal of concentrate; and adjustable means on the lower end of the header for selectively directing 'difierent amounts of water downwardly into the bottom of said chamber to agitate the contents thereof.

JOHN CAR'I'ER ANDERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,511,643 Trent Oct. 14, 1924 1,147,356 Allen July 20, 1915 86,249 Rae Jan. 26, 1869 2,353,152 Erck July 11, 1944 982,583 Flood Jan. 24, 1911 971,528 Dahlstrom Oct. 4, 1910 2,304,352 Griffiths Dec, 8, 1942 975,971 Malchus Nov,-15, 1910 1,047,673 McCarty Dec. 17, 1912 1,490,420 Elder Apr. 15, 1924 1,451,067 Elder Apr. 10, 1923 2,074,977 Bird Mar, 23, 1937 2,230,782 Maust Feb. 4, 1941 OTHER REFERENCES Taggart: Handbook of Mineral Dressing, 1945, page 47 of sec. 8.

Taggart: Handbook of Ore Dressing, 1926, pages 560 to 582. 

